feat(dashboard): activité 7 jours agrégée et capture pré-remplie (#19, #23)

get_project_activity(): fermetures/déplacements 7 j et dernier
événement par dépôt en une seule requête sur board_events;
la page /capture accepte ?repo= pour pré-remplir le dépôt.

app/models.py

@@ -368,6 +368,38 @@ def column_entry_times(repo_full_name: str) -> dict[int, str]:
     return {row["issue_number"]: row["entered_at"] for row in rows}
 
 
+def get_project_activity(days: int = 7) -> dict:
+    """Per-repo journal activity in ONE aggregated pass (issue #19).
+
+    For every repo present in the journal: closures and moves of
+    the last `days` days (journal stamps are UTC strings), plus
+    the most recent event ever seen for that repo.
+    """
+    from datetime import datetime, timedelta, timezone
+
+    cutoff = (datetime.now(timezone.utc) - timedelta(days=days)).strftime(
+        "%Y-%m-%d %H:%M:%S"
+    )
+    with get_db() as conn:
+        rows = conn.execute(
+            """
+            SELECT repo_full_name,
+                   SUM(CASE WHEN event_type = 'closed' AND created_at >= ?
+                            THEN 1 ELSE 0 END),
+                   SUM(CASE WHEN event_type = 'moved' AND created_at >= ?
+                            THEN 1 ELSE 0 END),
+                   MAX(created_at)
+            FROM board_events
+            GROUP BY repo_full_name
+            """,
+            (cutoff, cutoff),
+        ).fetchall()
+    return {
+        r[0]: {"closed": r[1] or 0, "moved": r[2] or 0, "last_at": r[3]}
+        for r in rows
+    }
+
+
 def get_metrics(repo_full_name: str | None = None, window_days: int = 30) -> dict:
     """Throughput and cycle time computed from the journal.